Gene Therapy: A Success for Four Patients

In a study performed at the Children's Hospital of Philadelphia with the help of researchers from the University of Pennsylvania, some young adult patients with Leber congenital amaurosis regained some ability to see. Leber congenital amaurosis begins at birth and causes complete blindness by age 40. One form of the disease is caused by a mutation in the retinal pigment epithelium 65 (RPE65) gene, which codes for a protein that helps convert vitamin A to a form that the retina can use to make rhodopsin, a light-absorbing pigment. If the gene is mutated and rhodopsin cannot be manufactured, the photoreceptors of the retina die.

In the study, a virus vector was used to deliver the RPE65 gene. No side effects were observed. Two patients who could only see hand motions before were able to read several lines of an eye chart, and one patient was able to efficiently navigate and obstacle course for the first time.

Plans have been made to treat younger patients, whose retinas are less damaged and stand to benefit more by the treatment, perhaps avoiding blindness altogether.

The full article may be viewed at: http://sciencenow.sciencemag.org/cgi/content/full/2008/428/2.